The invention relates to a method for processing vegetable products, in particular in vinification, and to an apparatus for implementing the above-mentioned method, with which apparatus known types of apparatuses can be equipped. According to the prior oenological art, vinification is conducted in special fermentation vessels, called fermentation vats, into which a mixture is inserted comprising grape must, crushed grapes and marc (skins and grape seeds). During fermentation, the must produces considerable volumes of carbon dioxide (about 0.5 hectolitres of gas per hour per hectolitre of must). The carbon dioxide produced pushes upwards the whole grapes and the crushed grapes, which form the so-called “cap” floating on the must contained in the fermentation vat. The cap tends to solidify, substantially preventing the solid parts that form the cap from remaining in contact with the must and releasing useful substances in the latter, such as anthocyanins (polyphenols), aromas and tannins contained in the grapes and responsible for the colour, flavour and bouquet of the wine. In order to overcome this drawback, the cap is periodically irrigated with a certain quantity of must taken from the base of the fermentation vat. For this purpose, it is necessary to provide the fermentation vat with an irrigating apparatus, which is substantially complex inasmuch as it comprises a pump for removing the must, one or more pipes for conveying the removed must to the top of the fermentation vat and an irrigating device placed inside the latter.
The must by means of which the cap is irrigated does not succeed actually in completely soaking the latter, because in the cap preferential outflow conduits are formed along which the must flows. The grape berries are gradually filled with the gas produced by the fermentation and consequently form a floating mass that becomes progressively more and more solid. The must can consequently wet only the zones of the cap that are near to the preferential outflow conduits, namely about 30% of the cap.
In order to overcome this drawback and wet the cap more effectively, breaking up and sinking the latter in the must by using mechanical apparatuses, for example pistons, is known. However, these apparatuses, in addition to being substantially complex and expensive, damage the grape berries and extract undesired substances from the skins of the latter.
Alternatively to the aforementioned mechanical apparatuses, vinification methods are known in which the carbon dioxide produced by fermentation is accumulated in the vinifying apparatus until high pressure is produced in the latter. The gas is then violently released outside, in order to break up the cap that has formed during fermentation. This method has the drawback of damaging the grape berries during the sudden expulsion of the gas and requires the use of autoclaves, namely sealed tanks able to withstand pressure above 0.5 bar.
Vinification methods are furthermore known in which the carbon dioxide produced by fermentation is accumulated in gaps made in the wall of the vinifying apparatus. The gas that is thus accumulated is then released more or less violently into the liquid must underneath the cap, so as to break up the latter. Also this system has the drawback of substantially damaging the grape berries.
Furthermore, in known vinifying apparatuses spring valves are used having the function of pressure-regulating valves. A drawback of this type of valve consists of the fact that the spring may jam, thus making the valve insufficiently reliable.